1. Field of the Invention
This invention relates to the recording and reproduction of images.
More particularly, the invention relates to a method of recording images on cinematographic film and a film camera for carrying out the method.
2. Description of Related Art
In published international patent application number WO 87/03972there is described a method of recording images onto cinematographic film in which a number of successive images are formed through a single lens system onto each frame of the film, successive images being recorded in light of different characteristics. In one form of the invention, two or more successive images are formed on each frame in light of different colours. For example, two successive images may be formed in red and cyan light. When the film, after processing, is projected using a conventional projection system, the red and cyan images in each frame are projected simultaneously on the screen. If the screen is viewed through a pair of spectacles providing an appropriate filter for each eye of the viewer, so that the red image is presented to one eye and the cyan image presented to the other, a marked stereoscopic effect is produced, as a result of disparities in the images produced by any movement of objects in the scene, or movement of the camera, between the successive exposures on each frame.
For example, suppose an object is moving from left to right across the scene, and that two successive images are recorded successively on the film, first through a red and then through a cyan filter and subsequently the two filtered images in each frame are projected simultaneously on the screen. From the point of view of the camera, the red image will correspond to the image of the object as seen from a point slightly to the right, as compared with the cyan image, the degree of misalignment or disparity depending on factors such as the speed of movement of the object and its distance from the camera. If the superimposed images are viewed through spectacles so that the red image is presented to the right eye and the cyan image to the left eye of the viewer, then the crossed horizontal disparity between the images will be equivalent to that caused by viewing an object suspended in front of the projection plane simultaneously from points spaced to the right and left of a central position, as in normal binocular vision. If one now considers an object moving from right to left across the scene, the right and left eyes will again be presented with different images, but they will now correspond to the uncrossed disparate images of an object behind the projection plane. Since this is an improbable stimulus in normal binocular vision, it would be expected that no stereoscopic effect, or an incorrect stereoscopic effect, would be observed. Similarly, an object moving vertically in the scene would give rise to vertically disparate images, which would not be expected to give rise to a stereo-scopic effect. If the camera undergoes translatory motion while viewing a three-dimensional scene, all objects in the scene, except those at optical infinity, will give rise to disparate images on each frame, the disparity varying appropriately with the distance of the object from the camera. Camera motion in one direction (right to left in the system described above) will generate disparities of correct sign, which would give rise to a strong steroscopic sensation for the entire scene when the projected image is subsequently viewed. Camera motion in the opposite direction will reverse the sign of all disparities, which might be expected to produce a reversed steroscopic sensation.
In practice it is found that reversed stereopsis rarely if ever occurs and the stereoscopic sensation is appropriate in direction whatever the motion of object or camera. It appears that the strong monocular cues (e.g. linear perspective, relative size, motion parallax) determine the depth impression of the picture and any horizontal disparities in the image can enhance but not override the depth sensation.